<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        html, body, iframe { height: 100%; }
        html { overflow: hidden; }
    </style>
</head>
<body>
<div style="height: 20px;background: red"></div>
<iframe src="demo.html" width="100%" scrolling="yes" frameborder="0"></iframe>
<div style="height: 20px;background: blue"></div>

</body>
</html>